Flight data recorders, the need for which became evident following a number of commercial crashes in the 1950s, required a robust form of information storage that could survive high temperatures and mechanical stress. Although wire and tape recording existed at the time and were later used for this purpose, the first technology applied to the problem was the embossing of instrument traces in foil made of a temperature resistent steel alloy called inconel. The traces could be read visually by holding a transparent graduated template against the foil.